1. Field of the Invention
This invention is a continuation-in-part application of U.S. application Ser. No. 584,635 now abandoned and relates to a creel for textile yarn processing machines, and a method of operating such a creel.
2. Description of the Prior Art
Textile yarn processing machines require a supply of unprocessed yarn, and from an economic standpoint it is preferable if the supply is continuous. Many types of such machines are of the multi-station variety and each station is supplied with yarn withdrawn from one of a large number of packages mounted in a creel structure standing near to the machine. Adjacent each package from which yarn is being withdrawn at any given moment, a reserve package is mounted, and the two packages have their yarn ends joined so that yarn automatic withdrawl is transferred to the reserve package when the first package is exhausted. The exhausted package is then replaced by a new full package which then becomes the reserve package. In this way the supply of unprocessed yarn to each station of the yarn processing machine is continuously maintained.
However, as yarn processing speeds have increased it has become more difficult and tiring for the machine operator to ensure that exhausted packages are replaced by full packages in good time to maintain the continuity of the processing, particularly in the case of a machine having a large number of yarn processing stations and when using large and therefore heavy packages. For example a modern false twist crimping machine has approximately 200 yarn processing stations and the supply packages can each be up to 34 kg in weight. Coupled with this increase in the weight of packages is their physical size which can be up to 445 mm in diameter and 250 mm in length.
It has always been an objective to reduce the overall size of textile machines. Typically false twist crimping machines are about 18,000 mm in length, having some 216 processing stations disposed 12 on each machine side to a bay. Consequently 12 full packages in use are required per side per bay and therefore 12 full reserve packages adjacent thereto.
Conventionally creels have been of the `gate` type which comprise a rectangular `space-frame` structure of metal tubes. On the upright ones of such tubes, package mounting arms are pivotally mounted, so that the packages are normally disposed within the space frame but may be pivoted so as to extend outside the space frame for loading and unloading purposes. To supply such a machine, 24 packages are required within the length of a bay on each side of the machine whilst only four full large size packages can be housed at one level. Consequently the creel is formed to be six packages high, with the uppermost packages being at a height of up to 3 meters. It is therefore very difficult for packages of 34 kg weight to be placed on the uppermost packaging mounting arms.
It has therefore been proposed to provide creels of the `rotary` type. Such creels are also of a metal tube `space-frame` construction but in this case the package mounting arms are normally disposed to extend radially towards the centre of each bay-sized creel section, being pivotally mounted on the vertical tubes disposed on the circumference of the creel section. The packaging mounting arms are again pivotal to extend outside the creel section for loading and unloading. With such an arrangement it is possible to have six packages on any one level so that the creel section can be only four packages high. However, even in such an arrangement the uppermost packages are at a height of about 2 meters, and with the large and heavy packages currently used this still presents a problem for the machine operator. Furthermore in order that the packages farthest from the aisles at the outside of the creel can be loaded and unloaded, the creel section itself is mounted so as to be rotatable about a central shaft pivot structure. It is required that processing of the yarn is maintained during loading of new packages and unloading of empty package tubes, and in order that the yarn path lengths are not altered during such rotation of the creel, the yarns are led adjacent the central pivot shaft of the creel. This leads to a complicated arrangement of yarn guides in order to prevent entanglement of the yarns. From U.S. Pat. No. 4,261,532 it is known to provide a creel in which a rectangular frame has mounted at each corner thereof a support for two yarn packages. The packages are each mounted on a spindle having its axis directed towards a respective yarn guide located on or adjacent the central axis of the frame so that yarn can be readily withdrawn from any one package to a central yarn guide. Each support is pivotal about its mounting at the corner of the frame so as to ensure correct alignment of the package carrying spindles supported thereon with a central yarn guide. However the dimensions of the frame place a constraint on the size of package which can be accommodated in the creel, and if a support is pivoted from its single position in which the spindles mounted thereon are correctly aligned with the central yarn guides, withdrawal of a yarn from a package on such spindle will be adversely affected if not prevented.